This invention relates generally to devices and methods for living tissue reshaping and, more particularly, to achieving three-dimensional bone lengthening and reshaping by distraction osteogenesis.
In many instances where the bone of a patient is malformed or deficient, correction can frequently be made by distraction osteogenesis. Bone defects of this type may stem from either congenital or acquired bone defects. Commonly these defects are birth defects, requiring treatment on infants. Examples of such defects include, for example, one leg, or arm, may be shorter than the other, due to bone deformity, or perhaps where the jaw or other bone structure is malformed or deficient, treatment is required to reshape such bone structure, trying to provide the appearance of normality, besides viable structure and functionality to the affected skeletal structure. Distraction osteogenesis utilizes the natural regenerative capability of the living tissue in bone to augment and shape the bone. Generally speaking, the bone is broken into two pieces and slowly separated, stimulating growth of bone in the gap to achieve a desired shape.
For example, treatment for patients with shortened leg structure is known. Where a patient has a thigh bone (femur) which is shorter on one side compared with another, the surgeon cut the bone in two at the site where new bone was desired. An external jacking mechanism, commonly referred to as a circumferential metal scaffolding, is attached to the bone sections above and below the bone cut by way of bone screws. Conventionally, the jacking mechanism includes a series of, for example, jack screws, or regular screws that can be tightened, to provide for lengthening of the bone structure, to achieve its normal length. By tightening the jack screws a certain number of turns per day, the separation between sections of bone infinitesimally increases, sometimes only approximately 1 mm (0.04 inches), per day, or the like, to gradually lengthen the bone. Additional bone structure, whether calcium deposit or other bone structure, grows in the intermediate gap, filling the gap and lengthening the bone, sometimes to significant lengths. Lengthening a bone by inches is common by these earlier methods.
The natural phenomenon of new bone creation across a gap that is slowly widened by the application of a distraction force has been well described, and has become known as the principle of xe2x80x9cdistraction osteogenesis,xe2x80x9d and is a common technique used by both orthopedic and craniofacial surgeons to lengthen or alter the shape of bone. Prior art devices have applied the distraction force largely through a screw drive mechanism, or other metal mechanical drive mechanism that imparts force to widen the gap by turning the screw a fixed amount per unit time.
One drawback of such a prior art method is scarring of the patient""s skin caused by the movement of the external jacking device with respect to the skin as the device extends the gap between the bone sections. Another drawback of transmitting tissue shaping forces through long bolts is the increase in device deflection as the device is placed more remote to the bone structure. This deflection results in less precise movement of the bone structure. Furthermore, prior art jacking devices external to the patient are often uncomfortable for the patient due to their bulk and weight. A few prior art devices disclose a distraction osteogenesis device incorporating a fully implantable jacking mechanism. There is a need, therefore, for a distraction osteogenesis device capable of providing linear, uniplanar, and multiplanar distraction osteogenesis with a fully implantable jacking device. Moreover, there is a need for a device that distracts tissue segments accurately and continuously in three-dimensions while reducing scarring and hiding itself from view.
Among the several objects of this invention may be noted the provision of a distraction device which is implantable within a body of a living thing for three-dimensional reshaping of living tissue; the provision of a distraction device which allows for substantially continuous distraction of living tissue for reshaping and regeneration of living tissue; the provision of a distraction device which is very small for implantation within small areas within the body of a small living thing, such as a child; the provision of a distraction device which reduces scarring of the skin by ensuring that portions of the device passing through the skin pass at a point where no displacement of the device occurs; the provision of a distraction device which moves external portions of the device to inconspicuous areas of the living thing""s body to hide scars better; and the provision of a distraction device which uses a hydraulic mechanism for fluid and forceful movement of regenerative living tissue.
Generally, a distraction device is disclosed for controlled movement of at least two sections of regenerative living tissue, such as bone, within the body of a living thing relative to each other in three-dimensions to foster reshaping the living tissue. The device comprises a first jack unit having a first extendable member adapted for attachment to one of the sections of living tissue. A second jack unit having a second extendable member is adapted for connection to the other of the sections of living tissue. An actuator is adapted for actuating extension of the extendable members to move the sections of living tissue apart for controlled regeneration of tissue between the sections. A joint interconnecting the first and second jack units is adapted to permit orientation of the first and second jack units relative to each other in three-dimensions. The jack units and joint are sized and shaped for implantation within the body for three-dimensional living tissue reshaping with movement of the device confined entirely within the body.
In another aspect of the present invention, a tissue expansion mechanism for expanding living tissue, such as bone, to foster reshaping of living tissue within the body of a living thing, is disclosed. The mechanism comprises an expansion device adapted for engagement with living tissue to foster reshaping the living tissue. The expansion device is capable of exerting a force with respect to the living tissue so that engagement of the expansion device with the living tissue induces the living tissue to expand according to the influence of the expansion device. The mechanism further comprises an automated control device adapted for connection to the expansion device to substantially continuously and automatically actuate the expansion device to foster reshaping of the living tissue.
In still another aspect of the present invention, a distraction hydraulic jack is disclosed for controlled movement of at least two sections of regenerative living tissue, such as bone, within the body of a living thing relative to each other to foster reshaping the living tissue. The hydraulic jack comprises a cylinder adapted for attachment to one of the sections of living tissue. A piston is partially received within said cylinder for movement of the piston with respect to the cylinder. The sliding, sealing inter-engagement of the piston and the cylinder form a sealed cavity within the cylinder. The portion of the piston not received within the cylinder is adapted for attachment to the other of the sections of living tissue. Both the cylinder and piston are sized and shaped for implantation within the body for living tissue reshaping with movement of the device confined entirely within the body. A hydraulic fluid source mounts externally to the body in fluid connection with the cavity for transmitting hydraulic fluid into the cavity. The fluid is incompressible such that additional fluid entering the cavity pushes the piston outward with respect to the cylinder such that the partially received portion extends outward from the end of the cylinder, thereby transmitting a force along the axis of the hydraulic jack so that the two sections move apart a specific distance.
In yet another aspect of the present invention, a method is disclosed for performing controlled movement of at least two sections of regenerative living tissue, such as bone, within the body of a living thing relative to each other in three-dimensions to foster reshaping the living tissue. The method comprises the steps of surgically exposing a portion of regenerative living tissue within the body and severing the regenerative living tissue into at least two sections. The method further entails attaching a distraction device to said at least two sections. The distraction device further comprises a hydraulic actuation system including a hydraulic fluid transport tube extending from the hydraulic actuation system to the distraction device for configuring the distraction device in three-dimensions for achieving three-dimensional distraction. The method comprises the additional step of implanting the distraction device entirely within the body of the patient and allow a free end of the fluid transport tube to extend from the body for connection to the hydraulic actuation system. The method comprises yet another step of regulating a flow of hydraulic fluid into the free end of the fluid transport tube from outside the body to control the hydraulic actuation system for controlled movement of the distraction device and the sections relative to one another at a specific orientation and distance to foster regenerative tissue growth between the sections.
Other objects and features will be in part apparent and in part pointed out hereinafter.